1. Field of the Invention
This invention relates to a Hall effect linear transducer of reduced size and power consumption, wherein gratings formed in a first magnetic plate are moved through a magnetic field relative to a Hall effect element and to gratings formed in a second magnetic plate in order to provide an indication of a linear dimension.
2. Statement of the Prior Art
Classical precision dimensional measuring devices utilize either lead screws and verniers or electronic indicators with analog type meters. These well known measuring devices are relatively difficult to operate and to read, have limited range, and provide relatively slow response times. Moreover, as a consequence of thread or gear wear, linearity errors may be introduced, thereby resulting in diminished reliability. What is more, many conventional electronic amplifier comparators operate with transducing characteristics which require a.c. line adaptability. This limits mobility and flexibility of transducer application. Otherwise, existing electro-mechanical linear transducers require too much power to be operated by batteries of suitable size. The aforementioned disadvantages are due, primarily, to the type of transducer utilized (e.g. a variable reluctance differential transformer type transducer usually requires a considerable amount of complex circuitry and large space consumption).
Particular examples of prior art displacement indicating devices which include a Hall effect transducing element arranged within a magnetic circuit are disclosed by the following U.S. Pat. Nos.: 3,164,013 Jan. 5, 1965, 3,195,043 July 13, 1965, 3,226,631 Dec. 28, 1965, 3,264,416 Aug. 2, 1966, 3,596,189 July 27, 1971, 3,906,359 Sept. 16, 1975, 3,835,373 Sept. 10, 1974.
However, none of the prior art patents listed above shows or discloses a magnetically operated linear transducer assembly including a first magnetic grating plate which moves in a magnetic field relative to a second, stationary magnetic grating plate and to a Hall effect element to produce a differential voltage signal across the Hall effect element so as to provide an indication of a linear displacement.